A coated tool including a coating layer formed by laminating a titanium carbonitride layer and an aluminum oxide layer on the surface of a substrate such as cemented carbide, cermet and ceramics is known.
In recent years, the efficiency of the cutting process has been increased, and there is an increasing opportunity to use the above-mentioned coated tool for cutting work on which the large impact is applied to the cutting edge, including heavy interrupted cutting. Under such severe cutting conditions, since a large impact is applied to the coating layer, chipping and peeling of the coating layer are likely to occur. Therefore, improvement of fracture resistance is required for the coating layer in addition to wear resistance.
As a technology for improving fracture resistance in a coated tool, a technique described in JP-A-2000-071108 (Patent Document 1) is known. Patent Document 1 discloses that a titanium carbonitride layer and an aluminum oxide layer are formed and there is a region where fine pores are distributed in a specific region in the titanium carbonitride layer.
In the present circumstances, further improvement of wear resistance and fracture resistance of the coating layer is required.